1. Field of the Invention
The present invention relates to a heat sink assembly, and particularly to an easily assembled and low cost heat sink.
2. Description of Prior Art
Since the successful introduction of integrated circuits devices, there has been a steady progression toward larger IC devices to permit inclusion of a greater number of functions of the devices. The result is that quantity of heat produced by these larger semiconductor devices is getting larger and larger. To effectively dissipate the produced heat, heat sinks are used. To firmly attach the heat sinks to the IC devices, retainers are used. Examples of prior art heat sinks and retainers are disclosed in Taiwan patent application Nos. 83218644, and 85200861. Referring to FIG. 4, there is shown a printed circuit board (PCB) 60 on which a substrate 61 and a chip 64 is mounted. Two apertures 62 are defined in the PCB 60. A conventional heat sink 50 includes a plate 51 with a large number of integral fins 53 thereon. A pair of protrusion tabs 52 is provided on opposite angles of the plate 51 and each has an aperture 54. A pair of retainers 40 is formed by plastic injection molding. Each retainer 40 has a shape of a nail with a stem 42 having a pair of barbs 44 at a lower end thereof. A pair of helical springs 46 is provided for providing an elastic force to firmly attach the heat sink 50 to the chip 64. In assembly, the retainers 40 are extended through the springs, the aperture 54 in the tabs 52, and the apertures 62 in the PCB 60 to reach a position in which the barbs 44 engage a bottom face of the PCB 60, the springs 46 being compressed between the tabs 52 and heads (not labeled) of the retainers 40 thereby pushing the heat sink 50 downwardly to cause the heat sink 50 to closely engage with the chip 64.
To retain the heat sink on the chip, the prior art needs four components, i.e., two retainers 40 and two helical springs 46, which cause the inventory to be complicated and costly. Furthermore, the helical springs 46 are expensive components, which cause the whole cost of the heat sink assembly to be high. Hence, an improved electrical connector is required to overcome the disadvantages of the prior art.